GMAC Practice Exam DS question #4

Is the OA E?

yes it is E. I had to do lot of scratch work for this and decided to guess and ended up guessing wrong.

Can you please explain ?? I tried finding slopes of 2 lines, I guess one slope has to be -ve for the lines to be perpendicular.

I can give it a try .
As question stem says that k and passes through (1,1) and (1,-1) thats means they intersect at x=1.They seeem to form vertical angles

ST 1 says that k and m intersect at (1,-1) which is exactly below that point.Nothing is said abt the angles as one shud be 90 for them to be perpendicular so INSUFF

ST 2 gives u a point for k and again nothing is said abt the angles it forms so INSUFF.

Similary when u combine these two ST no conclusion can be drawn.Hence E.

Any other suggestions are also welcome???

its_me07 wrote:I can give it a try .
As question stem says that k and passes through (1,1) and (1,-1) thats means they intersect at x=1.They seeem to form vertical angles

I'm not sure if I understand the verticle angle point you have made. (correct grammar??)

Anyway, If you draw these out quickly, which I have, you have two points. You just dont know which way the lines may pass.

Statement 1: Lines interesect at (1, -1). This doesn't indicate still which way they run. They could be verticle, but one line could be horizontal, or it could run on an angle. This statement helps to tell where they intersect, but doesn't reveal any information about their actual shape. INSUFFICIENT.

Statement 2: Line k (with points (1, 1)) intersects the x-axis at point (1, 0). This tells us that line k extends down to the x-axis as point (1, 0), but doesn't give any information about line m or does it give any information about either line's actual shape. INSUFFICIENT.

Therefore, answer is E - Statements 1 & 2 together are not sufficient.

when lines are at right angle to each other then they said to be perpendicular thats why i used the word 'verticl angles'.

ANyways thx fro the explanation